Refactor HostSetupDialog and HostInstallDialog.
1. Moved all the host installation logic to the HOST_INSTALL step in HostSetupDialog
2. On Windows host installation now occurs before the pin prompt when user enables remote connection.
3. HostInstallDialog now handles both the prompt (Linux/Mac) and non-prompt (windows) scenarios.
4. Renamed onDone and onError in HostInstallDialog to onOk and onCancel. The install prompt doesn't perform any task itself and won't incur any error so onOk an onCancel are better names.

This CL is a precursor to the change that enables automatic host installation for IT2Me on windows.

BUG=134215

Review URL: https://codereview.chromium.org/243993002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@269344 0039d316-1c4b-4281-b951-d872f2087c98

• remoting/webapp/connection_stats.js[diff]
• remoting/webapp/host_controller.js[diff]
• remoting/webapp/host_dispatcher.js[diff]
• remoting/webapp/host_install_dialog.js[diff]
• remoting/webapp/host_screen.js[diff]
• remoting/webapp/host_setup_dialog.js[diff]